LISTENING TO THE WIND TVA Experience with Installation and Operation of Ultrasonic Wind Sensors

1. LISTENING TO THE WINDTVA Experience with Installationand Operation of UltrasonicWind Sensors Kenneth G. Wastrack Doyle E. Pittman John E. Hatmaker, PE L. Wayne Hamberger Tennessee Valley Authority [NUMUG] Listening to the Wind

2. Background • Problem - Obsolete Wind Sensors • Difficulty obtaining spare parts (sensor, switch controller, etc) • Routine bearing replacement • History of mechanical failures • Requirements - Sensor Specifications • Comply with RG 1.23 requirements. • Wind direction +/-5 degrees. • Wind speed +/-0.5 mph. • Less maintenance than existing sensors. [NUMUG] Listening to the Wind

3. Vaisala 425AHUltrasonic Wind Sensor • Sonic Wind Sensors • All-electronic • Minimal maintenance • Vaisala* (formerly Handar) 425AH ultrasonic wind sensor most suitable • Manufacturer specifications • Capabilities for integration • System meets RG 1.23 [NUMUG] Listening to the Wind

4. System Performance [NUMUG] Listening to the Wind

5. Principle of Operation • Transmit signal along axis • Send in reverse direction • Calculate time differences • Convert to WS along axis • Repeat for other axes • Compute WD and WS [NUMUG] Listening to the Wind

6. Obtain Necessary Approvals TVA did not obtain prior NRC approval. Used 10 CFR 50.59 process and treated new ultrasonic wind sensor as “equivalent” to old wind vane/anemometer system. • Same mounting positions. • Same sampling intervals. • Same data processing. • No change from user point-of-view. Obtained prior approval from Plant Operations Review Committee (PORC) because of need for FSAR change. [NUMUG] Listening to the Wind

7. Develop Sensor Acceptance Criteria • Wind Direction • Orient sensor into each of 5 directions. • 360, 30, 150, 270, and 45º • Set wind tunnel speed to about 10 mph. • Verify that sensor output equals desired values (+/- 3º). • Wind Speed • Orient sensor to display wind direction of 45º. • Adjust wind tunnel speed. • 0, threshold<=1, 1, 2, 5, 10, 20, and 30 mph • Verify that sensor output equals desired values (+/- 0.3 mph). [NUMUG] Listening to the Wind

8. Perform Field Installation - I • Ultrasonic wind sensors were installed on the following dates: • Watts Bar (WBN) - October 2000 • Browns Ferry (BFN) - February 2001 • Sequoyah (SQN) – March 2002 Installations were conducted over two days according to normal Limited Condition of Operation (LCO) requirements for plant. Project was examined beforehand by maintenance and engineering personnel to address site-specific issues. Installation was not complete until a meteorologist verified data were acceptable and were transmitted properly. [NUMUG] Listening to the Wind

9. Perform Field Installation - II • Despite careful preplanning, problems occurred. • Proper survey equipment not available. • Need to modify onsite acceptance test. • Scheduling restrictions resulted in adverse weather impacts. • Need for change in planned installation at BFN. • Problems were addressed because individuals onsite during installation had authority to make adjustments to workplan. • After verifying correct operation, meteorologist provided final acceptance of the installation. [NUMUG] Listening to the Wind

10. Operational Experience Sensor calibration process has changed. Level of maintenance has decreased. Strip chart recorders are no longer used. Exceedances of calibration tolerances have decreased. Optical isolators provide effective lightning protection. [NUMUG] Listening to the Wind

11. New Problems Effect of “noise” on measurements. • Consider noise environment in site exposure criteria. • Consider ambient noise (e.g. thunder) during data validation. Configuration of sensor communications settings. • Extensive effort to send sensors to laboratory. • Developed methodology for in-situ configuration. Review/revise installation/exchange procedures. • Margin verifier issues. [NUMUG] Listening to the Wind

12. Data Changes - I Differences in wind direction percentages between the two types of sensors are generally within expected ranges. Watts Bar (10m) Browns Ferry (90m) [NUMUG] Listening to the Wind

13. Data Changes - II Browns Ferry (90m) Watts Bar (10m) [NUMUG] Listening to the Wind

14. Data Changes - III Significant changes have been noted in data recovery percentage and number of calm wind speeds observed. Watts Bar (10m) 20002001Diff. Data Recovery (%) 94.4 99.5 +5.1 Mean Avg. WS (mph) 3.57 3.90 +0.33 Number of Calms 210 9 -201 Watts Bar (90m) 20002001Diff. Data Recovery (%) 94.3 99.4 +5.1 Mean Avg. WS (mph) 7.58 7.42 -0.16 Number of Calms 4 0 -4 [NUMUG] Listening to the Wind

15. Other Tidbits - I Plan for final installation was to move sensor to 91-meter level. Comparison tests demonstrated that data from 93-meter and 90-meter levels are equivalent. Moving sensor as planned was a major project. Therefore, sensor test position became final position. Anemometer is mounted Due north of wind vane. [NUMUG] Listening to the Wind

16. Other Tidbits - II During the comparison tests on the BFN tower, 554 samples (~6%) blew through tower. Tower effects on measurements can be examined. Differences between 15-min. avgs (vane/anemometer - ultrasonic) WD (º)WS (mph)σΘ (º) Mean 0 2.1 -1 Range -100/+145 -0.4/+7.6 -57/+9 Std. Dev. 8 1.4 3 [NUMUG] Listening to the Wind

17. Conclusion Care must be taken to verify that ultrasonic wind sensors are suitable for operational applications. Changes should be well documented. Unexpected problems can occur. • ULTRASONIC SENSORS HAVE PROVEN • ACCEPTABLE FOR TVA AND REPRESENT • A SIGNIFICANT IMPROVEMENT. • Calibration tolerances are met consistently • Less corrective maintenance has been necessary. [NUMUG] Listening to the Wind